Hybrid Cross-Linked Bio Polymer-Epichlorohydrin/Fe3O4 Nanocomposite for As(V) Adsorption: Kinetic, Isotherm, Thermodynamic, and Mechanism Study

In the present work, iron-doped particle Carboxymethylchitosan nanocomposite cross-linked with epichlorohydrin (CMC-EPC/INC) were prepared, by a chemical precipitation method, characterized and evaluated for the removal of As(v) from an aqueous solution. The adsorbent was characterized by FT-IR, XRD, and SEM. Key parameters, including adsorbent dosage, pH, temperature, initial ion concentration, and contact time were investigated and found to be 0.4g, pH 4, 308K, 10 mg/L, and 120 min, respectively. Mechanism study reveals the availability of amino groups in biopolymer, which act as active adsorption sites towards the arsenic anion. On evaluating isotherm models of Langmuir, Freundlich, Temkin, Elovich, Redlich-Peterson, and Dubbin-Radushkovich, it was found that the Langmuir isotherm model fitted better compared to other models having a maximum adsorption capacity of 28.99mg/g, a high regression coefficient value of 0.9988, least chi-square value of 0.1781 and validated by D-R isotherm also. The process was found to follow monolayer adsorption and pseudo-second-order kinetics. Thermodynamic parameters such as ∆S, ∆H, and ∆G indicated the spontaneous, endothermic, and physisorption nature of adsorption. Competing anions did not cause a significant reduction in the adsorption behavior of arsenic. Successful regeneration of the adsorbent implies its applicability to the removal of arsenic from real-life wastewater.